Design and validation of a tunable inertial microfluidic system for the efficient enrichment of circulating tumor cells in blood.

The analysis of circulating tumor cells (CTCs) in blood is a powerful noninvasive alternative to conventional tumor biopsy. Inertial-based separation is a promising high-throughput, marker-free sorting strategy for the enrichment and isolation of CTCs. Here, we present and validate a double spiral microfluidic device that efficiently isolates CTCs with a fine-tunable cut-off value of 9 µm and a separation range of 2 µm. We designed the device based on computer simulations that introduce a novel, customized inertial force term, and provide practical fabrication guidelines. We validated the device using calibration beads, which allowed us to refine the simulations and redesign the device. Then we validated the redesigned device using blood samples and a murine model of metastatic breast cancer. Finally, as a proof of principle, we tested the device using peripheral blood from a patient with hepatocellular carcinoma, isolating more than 17 CTCs/ml, with purity/removal values of 96.03% and 99.99% of white blood cell and red blood cells, respectively. These results confirm highly efficient CTC isolation with a stringent cut-off value and better separation results than the state of the art.

Automated Chemical Sensing Unit Integration for Parallel Optical Interrogation.

We report the integration of an automated chemical optical sensing unit for the parallel interrogation of 12 BICELLs in a sensing chip. The work was accomplished under the European Project Enviguard (FP7-OCEAN-2013-614057) with the aim of demonstrating an optical nano-biosensing unit for the in-situ detection of various chemical pollutants simultaneously in oceanic waters. In this context, we designed an optical sensing chip based on resonant nanopillars (R-NPs) transducers organized in a layout of twelve biophotonic sensing cells (BICELLs). The sensing chip is interrogated in reflection with a 12-channels optical spectrometer equipped with an embedded computer-on-chip performing image processing for the simultaneous acquisition and analysis (resonant mode fitting) of the 12 spectra. A microfluidic chip and an automated flow control system composed of four pumps and a multi-path micro-valve makes it possible to drive different complex protocols. A rack was designed ad-hoc for the integration of all the modules. As a proof of concept, fluids of different refractive index (RI) were flowed in the system in order to measure the time response (sensogram) of the R-NPs under optical reflectance, and assess the sensors' bulk sensitivity (285.9 ± 16.4 nm/RIU) and Limit of Detection (LoD) (2.95 × 10-6 RIUS). The real-time response under continuous flow of a sensor chip based on R-NP is showed for the first time, obtaining 12 sensograms simultaneously, featuring the unit as a potential excellent multiplexed detection system. These results indicate the high potential of the developed chemical sensing unit to be used for in-situ, multiplex and automatic optical biosensing.

Resonant nanopillars arrays for label-free biosensing.

In our previous work we demonstrated for the first time, to the best of our knowledge, the experimental capability of resonant nanopillars (R-NP) arrays as biochemical transducers. In this Letter, we provide evidence of the capability and suitability of R-NP arrays on a chip to function as label-free optical multiplexed biosensors. R-NP are based on Si3N4/SiO2 Bragg reflectors with a cavity of SiO2. In order to demonstrate the biosensing performance, R-NP were biofunctionalized by the immobilization of IgG antibodies acting as a bioreceptor. This immobilization was carried out through the silanization of the pillars sensing surface with APTMS (3-aminopropyltrimethoxysilane). R-NP were integrated in eight different sensing arrays on a quartz surface chip. An optical fiber bundle monitored each sensing array vertically and independently after each biofunctionalization step, and subsequently after every recognition event of increasing concentrations of anti-IgGs. The results report a novel multiplexed optical biosensor made of eight sensing arrays on a chip with promising performance and yield.

Conjugation of active iron superoxide dismutase to nanopatterned surfaces.

Superoxide dismutase enzymes (SODs) are an essential part of the first line of cellular defense system against free radicals species. They catalyze the dismutation of superoxide radicals into oxygen and hydrogen peroxide. Although several studies have examined the attachment of superoxide dismutases to nanoparticles and nanostructures, never has been used a member of the Fe/MnSOD family. In this study, the behavior of plant origin FeSOD enzyme on three different nanopatterned surfaces was investigated as a function of covalent and electrostatic binding. Fluorescence microscopy was used to demonstrate that the protein is attached only to the gold layer. We also examined the activity of SOD by a colorimetric assay, and we have shown that the enzyme remains active after attachment to the three different surfaces under both kind of binding (electrostatic and covalent). This methodology could be useful for those who want to functionalize nanostructures with a SOD enzyme and test the activity. This process could be of great interest for the development of peroxynitrite and superoxide biosensors.

Efficacy and safety of cinacalcet for the treatment of secondary hyperparathyroidism in patients with advanced chronic kidney disease before initiation of regular dialysis.

AIM: To evaluate the compassionate use of cinacalcet for the management of secondary hyperparathyroidism in patients who are not on dialysis. METHODS: Patients with stage 4-5 chronic kidney disease (CKD) who were not on dialysis, had an intact parathyroid hormone (iPTH) level greater than 300 pg/mL, and had not responded satisfactorily to treatment with phosphate binders and vitamin D were prospectively studied. Patients received 6 months of compassionate treatment with cinacalcet, which was initiated at a dose of 30 mg/day orally and flexibly dosed thereafter based on iPTH levels. RESULTS: Twenty-six patients with a mean age±standard deviation (SD) of 58.8±16.1 years were enrolled in the study and included in the statistical analysis. The mean percentage change in iPTH levels from baseline after 6 months of treatment was -67.9±17.0%, with 92.3% (95% confidence interval (CI), 75.9-97.9) of patients showing an iPTH level within the limits recommended by Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines. The mean serum calcium concentrations had decreased significantly at the end of the study (-8.0±6.9%), while the mean serum phosphorus concentration had significantly increased (+8.3±17.0%). CONCLUSION: Our results suggest that cinacalcet may be a useful alternative for the treatment of secondary hyperparathyroidism in pre-dialysis patients who are unresponsive to other treatments. The hypocalcemia and hyperphosphatemia reported in previous studies may not occur if a moderate dose of calcimimetics is used in patients with marginal glomerular filtration rates, especially if combined with vitamin D analogues and calcium-based phosphate binders.